Alistair Darling will strike an upbeat note about the prospects for the economy as he delivers a budget designed to help Britain grow its way out of the deepest recession since the second world war.

Seeking to establish clear dividing lines between Labour and the Conservatives, the chancellor used a Treasury podcast to warn that the economy was at a crossroads and needed continued support from the government.

Darling will say that the parlous state of the public finances rules out a pre-election giveaway and will instead announce plans for a green infrastructure bank and financial help for credit-starved businesses. Firms are hopeful that the chancellor will also abandon plans for a 1p increase in the rate of corporation tax paid by small companies and freeze petrol duty.

"This budget isn't just about securing our recovery, but critically it is about making the big decisions for the future", Darling said.

With figures in the last week showing both unemployment and inflation falling, Darling will express optimism that the UK can avoid a double-dip recession: "I'm confident about the future, I think government can make a real difference.

"It can't do it all itself, it needs people, it needs imagination, it needs flair – but government can make a difference to the future of our country for the next 10 or 20 years."

Against a backdrop of Britain's biggest peacetime budget deficit, the chancellor is expected to produce a set of proposals showing how he will achieve more than £11bn of efficiency savings department by department. The Treasury will make a virtue of its willingness to detail the savings, and so give credibility to its deficit reduction programme.

In a budget runup that has lacked the internal tensions of the pre-budget report in December, Darling has been the dominant figure. Co-operation has been achieved largely by making it clear to all departments there will be no tax rises to bail them out.

In an attempt to reach the efficiency savings, on top of £5bn of programme cuts, the Treasury has asked each ministry to lift the efficiency of its finance, IT and HR operations up to the upper quartile of public sector performance, requiring a radically different approach. All departments have also been asked to make a contribution to reducing the senior civil service by 20%.

Departments have also been asked to halve their consulting bill and their maketing spend by 25%. In addition they have been asked to detail asset sales, future plans for collobarative purchasing and energy efficiency. Ian Smith, in a report, will advise the government on the scope for further relocations out of expensive parts of London and the south-east.

The communities secretary, John Denham, will set out the ballpark savings to be expected from 13 Total Place pilot schemes designed to increase collaboration between public sector agencies in local areas.

Darling said: "We're reaching a pretty critical stage where it's something of a crossroads. Countries right across the world are coming out of recession and that's good. And of course we will take action to get our borrowing down, halving our borrowing over a four-year period.

"But we know that if we're going to get the jobs in the future we've got to have a budget that ensures that we have growth. And of course government can't do everything itself, but what government can do is help unlock private sector investment so that we can bring the new investment that will bring the jobs that we need in the future.

"We know that across the world our competitors are not standing still. Countries in the far east and South America [are] making big changes so that they are ready to face the future."